The article by Pfeifer et al. describes the exacerbation of cerebral hemorrhages seen in an aged APP-transgenic model following passive administration of anti-Aβ antibodies directed to amino acids 3-6. This particular transgenic mouse, called APP23, is described by the authors in a previous paper as a "spontaneous hemorrhagic stroke mouse model" (Winkler et al., 2001
). At approximately 19 months of age onward, the mouse exhibits severe cerebral amyloid angiopathy (CAA), which is associated with recurrent hemorrhages as the mice age. Moderate to severe cerebral vascular amyloid also exists in approximately 26 percent of Alzheimer’s disease patients, as well, though the rate of hemorrhages is less than that seen in the APP23 mouse (approximately five percent of AD cases; see Greenberg et al., 1998
When the authors gave 21-month-old APP23 mice a monoclonal antibody directed to Aβ3-6 once a week for five months, they saw that the rate of...